Yes. You can export ProTreat results to Microsoft Excel and Word files for use in generating documents for customer and internal use. And the original ProTreat results files can be sent to and read by anyone you wish because ProTreat's GUI is freely available from this site as a download.

Yes. For as long as you hold a license, you will always have the most up-to-date ProTreat software. There is no additional charge for updates, and you can even send your clients readable ProTreat results files because we provide a freely downloadable GUI that will let them open, read, print, and export ProTreat files.

Yes. ProTreat's amine capabilities include MEA, DEA, DGA, DIPA, MDEA, AMP, Piperazine, and amino acids. These amines can be used singly, and in two- and three-amine mixtures. In addition, ProTreat simulates all the Ineos GAS/SPEC* solvents, many of which are amine mixtures. Plus, ProTreat accounts for the effects of Heat Stable Salts on treating and this allows for simulating the effect of stripping promoters on solvent regeneration. Other amines and promoters are being added all the time, along with physical solvents, glycols for dehydration.

ProTreat is just as much at home with a packed column as with a trayed one. It divides the packed height into a number of very short segments (to approximate the continuous nature of packed column contacting). The mass transfer characteristics of packing (both random and structured) depends very much on packing type, size and material. For example, large packings have low pressure drop but also relatively poor mass transfer performance because of their (1) low surface area per unit volume, (2) less frequently interrupted liquid flows, and (3) less intensive vapor mixing. Small packings are much more efficient, but at the expense of higher pressure drop. Obviously, the shape and structure of the packing affects the hydraulics of vapor and liquid flow, so mass transfer performance depends on packing type (various vendor-branded rings, saddles, etc.) ProTreat uses basic information supplied by the major vendors for all their packings to predict the performance of a specific installation. The simulation is direct. It does not use theoretical stages, HETP's, or HTU's. If your column contains 40 feet of #2 stainless steel CMR's, that's exactly how ProTreat simulates it.

ProTreat's mass and heat transfer rate model is general purpose. It is applied with equal validity to absorbers, regenerators, and flash-gas reabsorbers. All tower internals are correctly modeled as trays or packing in full detail, including swages in tower diameter from one section to another, if desired. You can even accurately model a column with trays in one section and packing in another, as well as change tray and packing types and other details across multiple sections in the same column. Columns can be modeled with their diameter specified or they can be sized to achieve specified percentages of tray jet flood, downcomer flood, and packing flood.

Yes. ProTreat generates plots of phase density, viscosity, and heat capacity as a function of the actual tray number for all types of columns.

Optimized Gas Treating makes available technical support by telephone and email. The most effective way for us to help you is for you to provide us with the input file (or a sanitized copy) you are trying to run. Although ProTreat does a lot of preprocessing of data, it's not always possible to catch 100% of the errors and inconsistencies 100% of the time. A copy of the ProTreat data file is the fastest way to help.

It matters to both. Different types of tray (bubble, sieve, valve) introduce the vapor into the liquid in different ways and this generates different vapor- and liquid-side mass transfer coefficients and interfacial areas. Each tray type has a different correlation in ProTreat.

Chemical reaction kinetics pertains specifically to the reaction between CO2 and the amine (or amines in blended or promoted solvents). The CO2 transfer rate (absorption/stripping) is controlled primarily by resistance in the liquid phase; in other words, by the liquid-side mass transfer coefficient. The CO2 has to diffuse through a thin, resisting, mass-transfer film in the liquid at the gas-liquid interface (thinner than the thickness of the liquid film flowing over packing, for example). This free (unreacted) CO2 can have its concentration greatly reduced (absorption) or increased (stripping) by the reaction. In effect, reaction thins the mass transfer film, and thereby lowers its resistance. This is quantified by a so-called enhancement factor. We hasten to emphasize that this enhancement factor is definitely not an empirical correction parameter. Quite the contrary - it comes from solving the reaction-diffusion equations that describe chemically-reactive mass transfer at the mechanistic level. The reaction-diffusion equations contain all the relevant information about molecular diffusion, reaction kinetics, and reaction equilibria. The enhancement factor is a well-defined dimensionless number or group just like Reynolds and Prandtl numbers - it is not an empirical adjustment parameter.

Most physical and transport properties are empirical correlations of data from laboratory measurements. They include data supplied by solvent vendors, literature data, and data measured by Optimized Gas Treating. The effect of acid gas loading on most properties is accounted for in the correlations.

They have been - at least heat transfer rate models have - for nearly a century. Mass transfer rate modeling is another story. Because of the large number of components being transferred (not just heat), and the large number of trays in columns, mass transfer rate models have had to wait for the ready availability of high performance computing power. Today we have desktop computing power that far exceeds most mainframes of only 20 years ago.

When you design a heat exchanger, you are using a heat transfer rate model that employs tube-side and shell-side heat transfer coefficients derived from correlations that account for such parameters as tube passes, shell-side baffling arrangements, tube Reynolds and Prandtl numbers as well as a variety of physical and transport properties. Heat exchanger design methods account for detailed equipment geometry, and the hydraulics of flow through the tubes and shell. It is now possible to apply exactly the same principles to the complex separation of materials in trayed and packed columns. You wouldn't treat a heat exchanger as an efficiency-modified equilibrium stage, and it's no longer necessary to treat columns that way either. ProTreat's mass and heat transfer rate model applies sound, tried-and-true, fundamental engineering principles to amine treating plant design and the detailed analysis of their columns.

In and of itself, the residence time is not relevant to gas treating, or indeed to any other mass separation operation. As a mass and heat transfer rate based model, ProTreat's column module uses gas- and liquid-side mass transfer coefficients and interfacial contact area, not residence time. It is true that a deep weir on a tray, for example, will provide increased interfacial area and also has longer residence time. However, interfacial area and mass transfer coefficients, not residence time, determine the mass transfer rates of the species. Residence time is an associated parameter, but not a determining one. It has the same relevance to mass transfer in columns as it does to heat transfer in heat exchangers - absolutely none! It is used by some simulators as an adjustment parameter to force at least partial agreement of theoretical-stage simulation with measured column performance. But it has no place in a true mass and heat transfer rate model.

A ProTreat simulation is as valid with respect to the effect of pressure as the Peng-Robinson and Redlich-Kwong-Suave equations of state. However, ProTreat does not allow for the presence of liquefied acid gases nor for the presence of two liquid phases, i.e., three-phase systems. Within this constraint, systems having pressures in excess of 1500 psi (100 bar) can be accurately modeled.

Because it requires detailed tower internals information, ProTreat does indeed need quite a bit more user input information than other simulation packages. That's what gives it such a tremendous simulation advantage. To help ensure that all the necessary data have been entered, and that the data are consistent and reasonable, ProTreat does extensive data preprocessing before even starting a simulation. Missing data and inconsistencies are pinpointed and reported immediately.

There are no user-adjustable parameters (e.g., tray residence time) to force ProTreat results into agreement with plant data. ProTreat is a truly predictive simulation package. It tells you what your plant should be doing, and it provides you with the resources to help you find out why it may be falling short, and how to improve its performance.

ProTreat currently models treating solutions using (1) the amines MEA, DEA, DGA®, DIPA, MDEA, AMP, Piperazine, Sodium Glycinate, and Potassium Dimethylglycinate (amino acids), (2) a physical solvent, the dimethylether of polyethyleneglycol (DMPEG, also known as SELEXOL™, Genosorb® and Coastal AGR®) and (3) triethylene glycol (TEG) for gas dehydration. Solvents can contain one amine as well as two and three amine mixtures. Amine concentrations cover the full spectrum of strengths found in commercial solvents. For example, ProTreat uses DGA data for strengths up to 70 wt% DGA. System pressures are limited only by the validity of the Peng-Robinson and Redlich-Kwong-Suave equations of state, provided the liquid never splits into two liquid phases. Excellent predictions of performance data have been made at pressures up to 150 bar.

ProTreat has several highly significant benefits:

  • ProTreat never asks you to translate theoretical stages into tray counts and heights of packing because it only ever uses real trays and real packing in its calculations.
  • ProTreat is completely predictive and can model completely new applications without needing field performance data in a similar application.
  • ProTreat uses a mass and heat transfer rate based model that treats columns as real pieces of equipment complete with column internals details. Parameters like the number of tray passes, tray type, weir height, packing size, type and material all make a difference to the way your column performs. Other packages don't consider tower internals except to do pressure drop and flooding hydraulic calculations - ProTreat uses all the internals details for the separation too.
  • ProTreat models regenerators with the same high degree of accuracy that it handles absorbers. As you know, regenerators have a lot to say about how well an absorber treats and about process economics. Regenerator simulation is problematic for other amine treating simulators. For ProTreat, a regenerator is just another column.
  • ProTreat models the effects of heat stable salts (HSSs) on process performance. This is especially important in refinery applications where HSSs are always present, and usually in significant concentrations. This capability is extremely useful for making reclaiming decisions because too clean a solvent can fail to treat adequately in tail gas units, for example.
  • ProTreat models the effect of phosphoric acid stripping promoter on regenerator performance and lean amine quality. Using phosphoric acid is very useful way to drop lean H2S loading in MDEA systems to values lowered by factors of 10 to 100 times, and achieve much lower H2S leaks from tail gas and acid gas enrichment units.
  • ProTreat models aMDEA® extremely well. This is a piperazine promoted MDEA -based solvent that is widely used, most notably in ammonia and LNG plants.
  • ProTreat allows many solvents being considered for post-combustion CO2 capture to be simulated with high accuracy. Solvents of particular interest include piperazine promoted AMP, and promoted amino acids. Simulation capabilities in this, and other application areas include full-scale, pilot-scale and lab-scale units.

A mass and heat transfer rate model for amine treating relates the transfer rate (absorption or stripping) of each acid gas to the:

  • gas- and liquid-side mass and heat transfer coefficients and the interfacial contact area
  • driving force for mass and heat transfer (related to phase equilibrium and how far removed from it the system is)
  • effect of reaction kinetics and mechanism on the mass transfer process

Mass transfer coefficients and interfacial areas depend very strongly on the specifics of the tower internals and the hydraulics with which the internals are operating (e.g., gas and liquid flow rates and phase properties). Parameters such as

  • tray type
  • number of passes
  • weir height
  • type of packing
  • packing size
  • packing material (wetability)
play a very important part in determining mass transfer coefficients.

Reaction kinetics is another important factor in selectivity, that plays a huge role in enabling activated amine systems (such as mixed amines and piperazine-activated MDEA) to function properly when CO2 removal is the goal. So, the separation is determined completely by the relative rates of mass and heat transfer of the acid gases (and water), not just by phase equilibrium and reaction kinetics.

A simulation package has flexible flowsheeting capability if it allows you to draw, configure, and run any processing scheme you need to. Some packages provide you with only a choice from a handful of fixed, pre-drawn flowsheets, and often none of them fits your needs. ProTreat's drawing package, inspired by CorelDraw, allows you to set up any processing scheme you like, in a completely natural and intuitive way.

Just as heat transfer rates in exchangers are decided by shell-side and tube-side heat transfer coefficients and tube surface areas, mass transfer rates are decided by gas- and liquid-side mass transfer coefficients and interfacial gas-liquid contact areas. These coefficients and areas are characteristic of (and are different for each of) the particular internals being used or considered. They depend on tray type, passes, and weir height, and on the packing geometry (shape), size, and material (wetability). These characteristics depend themselves on fluid phase properties (viscosity, density, surface tension), and on phase flow rates. So the separation, the selectivity, and the product stream compositions depend on all these factors, quite in addition to VLE and reaction kinetics.

If you're designing a new amine treating system, or evaluating a solvent changeout, ProTreat can tell you the treated gas composition to expect and what a change in tray count or packed depth will have. In selective treating, tower internals have a tremendous impact on the selectivity actually achieved. At best, other simulators use liquid holdup as the only internals parameter controlling selectivity - this is a gross oversimplification. ProTreat addresses the details of internals and their effect on selectivity. Even the effect of inter-stage cooling on performance is accurately predictable. ProTreat can tell you exactly what performance a specific packing will achieve and how one packing performs compared to another. Will packing give equivalent performance to trays? ProTreat will give you the answer. No other amine simulator can.

ProTreat provides metric, SI, and US (still called English by some) units. But you aren't stuck with one of the other. You can create and save your own unique system of default units, then over-ride your customized set (or any other default units set) at any time, for any quantity. And ProTreat contains all the usual units peculiar to gas treating. You can even define standard atmospheric pressure for a particular plant location.

The term "rate model" is used by some people to describe the use of a type of stirred-tank reactor model for the reactions taking place between dissolved gas and the liquid on a tray. This type of reaction effects modeling assumes reaction rate controls absorption of CO2, but it doesn't. Mass transfer resistance does. In any case, kinetics (dynamic) and equilibrium stages (static) just don't go together. This kind of model is not to be confused with a mass and heat transfer rate model. The term "rate-based model" should properly be reserved as shorthand for a mass and heat transfer rate model, not for an empirical correction to ideal stages.

A mass and heat transfer rate model doesn't even use the concept of ideal or equilibrium stages. It applies the same kind of fundamental rate principles to mass (and heat) transfer on contact trays and packing, that you take for granted in the context of heat exchanger design. It uses the mass transfer characteristics of the tower internals to calculate the actual rate of transfer of the acid gases and water between the vapor and liquid phases. The degree to which the phases are not in equilibrium is the driving force for mass transfer, and it's different for each component. If it's not a mass and heat transfer rate model, it's not a rate-based model, and it's nothing like the real thing.

Other packages deliver results in terms of the number of theoretical stages, in the absence of field data and/or experience they cannot predict column performance for selective treating, they cannot deal properly with packing and unusual applications like acid gas enrichment, and they leave you wondering how to translate theoretical stages into real tower internals. ProTreat uses a column model based on sound mass and heat transfer rate fundamentals. It has no adjustable parameters and it predicts performance without needing field data of any kind. You are never asked to translate theoretical stages into tray counts and packed bed heights, or provide tray or packing liquid residence times, or tray efficiencies and HETPs. Packing and acid gas enrichment present no challenge at all. And ProTreat is a fully flexible flowsheeting package - it is not limited to a handful of fixed, predefined flowsheet configurations.

One of ProTreat's most important attributes is the ability to predict absorber and regenerator performance for a wide variety of tray and packing internals. This is especially valuable in selective treating applications where a column is neither rich-end nor lean-end pinched. Predictions are for real trays and real packing from specific suppliers in specific sizes and materials. Reference is not made to theoretical stages. Equipment vendors don't sell theoretical stages; they supply physical trays and packing, and you need to be able to make your specifications in those terms. Only ProTreat can do that reliably. ProTreat uses such a detailed, engineering-science-based model for a column that you are really simulating a virtual plant, correct in every respect, and truly predictive in every sense of the word.


View past issues of The Contactor™ and ProTips™.

Subscribe to: